The upgrade might take 20 hours or more , according to recent PC magazine article. For a smoother ride, it is recommended to do a fresh installation , which is also best after using Windows 7 for a few month later. Still confused? Get help from Ina Fried (CNET, as of 2009-Nov-2) who might give you a good relook on his article titled Windows 7 upgrade version: The do and don'ts found on http://news.cnet.com/8301-13860_3-10388567-56.html The excerpt, "...The difference between an in-place upgrade and a "clean" installation, in this instance, means backing up one's data, installing Windows 7, restoring the data, and reinstalling all Windows programs. Windows 7 upgrade disks can be used to do this clean installation and will recognize the previously installed version of Windows. So if you don't have any previously installed Windows on the machine, you will want to get yourself a full copy of Windows 7..." Upgrade does not take 20 hours! It took me 2-3hours. I did a upgrade from Vista Prem to Win 7 Ultimate around 2-3 hours. Maybe if you did a upgrade on a very old system, with lots of junk, files, I guess it could take 20 hours..